A retroreflective sheet that reflects incident light toward a light source is conventionally well known, and is employed in various fields leveraging its retroreflective property and superior visual recognizability in dark places.
For example, a sign such as a street sign and a construction sign employing a retroreflective sheet reflects light from a light source of a headlight of a car running in the dark places for example at night toward the light source, in other words toward the running car, thereby providing superior visual recognizability to a driver of the car who is a recognizer of the sign and allowing clear communication of information.
As a retroreflective sheet employed in the abovementioned application, an encapsulated-lens retroreflective sheet and a prism-type retroreflective sheet (for example a triangular pyramid type cube corner retroreflective sheet), which is superior in the retroreflective property, are more and more widely employed from year to year.
By employing a colored acrylic resin film as a surface material for the retroreflective sheet used as a street sign and a construction sign, superior properties such as weather resistance and visual recognizability can be provided to the retroreflective sheet.
As a colored acrylic resin film for the retroreflective sheet surface material, a colored acrylic resin film of which chromatic coordinate (x, y) according to the XYZ colorimetric system is within a specific range is disclosed (Patent Documents 1 and 2).
Colors of the colored retroreflective sheet are white, yellow, red, orange, green, and blue, and a chromatic coordinate is defined for each color in the standard.
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2005-112982
Patent Document 2: Japanese Unexamined Patent Application, Publication No. 2008-208197